Field of the Invention
The present invention relates to an image processing method and an image processing apparatus which perform correction processing on an abnormal value of X-ray image data.
Description of the Related Art
In a one-dimensional semiconductor detector or a two-dimensional semiconductor detector, an abnormal value in only one pixel is occasionally detected due to, for example, the failure of a pixel caused such as by the incidence of strong cosmic rays, the accumulation of noise or degradation in long exposure. Since the number of such pixels that appear is limited, the adverse effect on the actual measurement and analysis is limited.
However, since the appearance of a pixel with such an abnormal value is likely to damage the reliability of an image, a pixel with an abnormal value has been conventionally corrected. For example, a method is known which performs a measurement two times under the same conditions, compares the obtained two images and thereby identifies an abnormal value.
A method is also known which divides a necessary exposure time into a plurality of short times to perform capturing, collects image frames captured in the individually divided times, focuses on a certain pixel to arrange the data in the individual times in order of size of the data and removes a predetermined number of pixels from the largest or the smallest size. For example, in an imaging apparatus disclosed in patent document 1, when the brightness of image frames obtained in a division period is equal to or more than a predetermined brightness, the image frame per division period is displayed on a display device whereas when the brightness is lower, image frame is determined not to be displayed.
On the other hand, a method is also known which performs exposure and capturing while shaking a detector, grasps a pixel indicating an abnormal value and thereby produces a correction mask. For example, in an X-ray analysis method disclosed in patent document 2, a first data set and a second data set measured while displacing the position of a detector are overlaid on each other, and thus a pixel indicating an abnormal value is detected.